To compare 24-hour ambulatory blood pressure monitoring with existing laboratory methods, and to investigate the impact of BP and age on systemic hemodynamics.Design and method:
Cardiac output (CO) and systemic vascular resistance (SVR) were analyzed in 3 sub studies. Sub study A: 24-hour PWA (MobilOGraph, IEM, Stolberg, DE) was performed in a convenience sample (n = 66) stratified into 3 groups by systolic BP levels (<120, 120–139, >139 mmHg) and separately stratified by age (<55, >/ = 55 years). Sub study B: Each individual PWA was analyzed for within individual trends in CO and SVR. These trends were compared to the trends obtained from Sub study A. Sub study C: supine hemodynamics and echocardiographic parameters measured in a reference population developed in our laboratory (n = 78) were compared to 24-hour PWA means(Sub study A).Results:
BP was independent of CO in all 3 sub studies, overall and for each BP subgroup. Thus, there are very strong inverse relationships between 24-hour SVR and 24-hour CO for each BP group (p < 0.000 each) in each sub study, with a parallel upward-rightward shift of the respective SVR-CO isobars as BP increases. Figure 1 (left panel) shows the SVR-CO isobars for each BP group in Sub study A. Nearly identical relationships were also found in sub studies B and C. Figure 1 (right panel) demonstrates respective SVR-CO isobars for younger and older individuals, demonstrating only a rightward shift in the SVR-CO isobar.Conclusions:
1) Hemodynamic analysis using 24-hour ambulatory PWA is feasible.Conclusions:
2) Sustained hypertension is associated with an upward-rightward shift of the SVR-CO isobar in proportion to the degree of BP elevation, indicating that the underlying hemodynamic abnormality in hypertension at any stage is both inappropriately high CO and inappropriate high SVR.Conclusions:
3) Age effects on hemodynamics are more complex.